Evaluation of the GPS Wide-Area Augmentation System (WAAS) Ionospheric Grid Algorithm During the Peak of the Current Solar Cycle

M. Bakry El-Arini, John A. Klobuchar, Patricia H. Doherty

Abstract:	The Federal Aviation Administration (FAA) Satellite Program Office, ARD-70, is developing a Wide Area GPS Augmentation System (WAAS) to support a precision approach capability down to or near the lowest Category I (CAT I) decision height (DH) of 200 ft. In one of the candidate architectures under development, a vector of corrections is sent to the user via geostationary communication satellites (e.g., Inmarsat). This correction vector includes components for ionospheric, clock, and ephemeris corrections. The ionospheric corrections are based on the wide-area differential GPS ionospheric grid algorithm developed previously by MITREKAASD and the Air Force Phillips Laboratory (AFPL). The purpose of this paper is to evaluate the performance of the grid algorithm using measured data during January and February 1991, a period that falls very close to the peak of the current solar cycle. The data was collected by Jet Propulsion Laboratory (JPL) using a network of dual- frequency receivers. The distance between the user and remote sites is greater than 1000 mi. It should be noted that the results in this paper represent a type of upper bound on the performance of the grid ionospheric algorithm due to the relatively large distances between user and remote sites and the higher than normal solar flux densities. This distance is specified as 500 mi in the current WAAS architecture.
Published in:	Proceedings of the 1994 National Technical Meeting of The Institute of Navigation January 24 - 26, 1994 Catamaran Resort Hotel San Diego, CA
Pages:	961 - 968
Cite this article:	El-Arini, M. Bakry, Klobuchar, John A., Doherty, Patricia H., "Evaluation of the GPS Wide-Area Augmentation System (WAAS) Ionospheric Grid Algorithm During the Peak of the Current Solar Cycle," Proceedings of the 1994 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1994, pp. 961-968.
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